Since in a reciprocating grate cooler the cooling air is delivered through the interior of the cooler housing located below the grate elements, this interior of the cooler housing is under positive air pressure. A drive mechanism which serves to produce the thrust motion of the grate elements is usually arranged outside the cooler housing and passes by means of a driving shaft through an elongated opening which is provided in a side wall of the cooler housing.
In order to prevent the escape of cooling air and the discharge of powdered particles of the cooled material through this elongated opening, in the previously known constructions special measures have been provided for dustproof and airtight sealing of this opening.
In a known construction of this type a sealing plate which is firmly connected to the driving shaft and therefore movable with it is pressed by spring force against a stationary sealing plate which is connected to the side wall of the cooler housing. If the movable sealing plate is moved to and fro by the driving shaft during the thrust motion, then the sealing plates which lie under spring pressure against one another are constantly rubbed against one another. In order to keep the wear on the abraded rubbing surfaces within limits, attempts are made continuously to press grease between the rubbing surfaces by means of a central lubricating arrangement.
The sealing between the driving shaft and the movable sealing plate is achieved in this known construction by a stuffing box which is also pressed by spring force against the driving shaft and the sealing plate. In order to keep the movable sealing plate in its position on the driving shaft it is guided through a guide strip.
The principal disadvantage of this known construction is the severe wear on the sealing elements which are movable relative to one another, and also the high costs associated with the central lubrication as well as the necessity for frequent maintenance. A particularly unfavourable aspect is that disruptions to this sealing system (for instance failure of the central lubrication caused by contaminated grease) can lead to a shutdown of the reciprocating grate cooler and thus in certain circumstances to a temporary failure of the entire kiln installation.
The object of the invention, therefore, is to avoid these disadvantages and to provide a reciprocating grate cooler of such construction that the costs associated with the airtight and dustproof sealing of the cooler housing are substantially reduced and a high degree of freedom from disruption of the installation is produced.